Mine would be a combination of XM radio and my radar detector. I also have a Garmin Street Pilot GPS, Cobra CB Radio with NOAA, 2-way radios for trailing, and a mini-referigerator. The fridge only goes with me when I want it to, but it's small enough to fit between the seats in my standard cab!
XM Radio is, by far, the most innovative and entertaining source of music, information, news, and talk-shows in the world! The Commercial free channels have me TOTALLY spoiled! I've now had to upgrade my digital cable service at home to incorporate DVR, so I record my TV shows, and fast forward through the commercials.
If you buy a satellite radio system, you too will agree it's the best there is. My humble opinion is XM is better than Sirius, but I don't have any experience with Sirius. Who can NOT be satisfied with constant, consistant broadcast nationwide (except in tunnels!!!) It's the BEST!